Electronic paper, also referred to as e-paper, electronic ink or e-ink, is a display technology that was developed to mimic the appearance of regular ink on paper. Unlike a conventional flat panel display that uses a backlight to illuminate its pixels, electronic paper reflects light like ordinary paper and is capable of holding text and images indefinitely without drawing electricity or using processor power, while allowing displayed text and/or images to be changed. One important feature is that the pixels be image stable so that the state of each pixel can be maintained without a constant power supply.
Electronic paper was originally developed to overcome some of the limitations of computer monitors. For example, the backlighting of monitors is hard on the human eye, whereas electronic paper reflects light just like normal paper. Electronic paper is also easier to read angles than flat screen monitors.
The first electronic paper was developed in the 1970s by Nick Sheridon and consisted of polyethylene spheres between 20 and 100 micrometers across. Each sphere was composed of negatively charged black plastic on one side and positively charged white plastic on the other side. The spheres are embedded in a transparent silicone sheet, with each sphere suspended in a bubble of oil so that the sphere were allowed to rotate freely. A voltage having a predetermined polarity applied to each sphere determined whether the white or black side of the sphere would rotate so as to face-up, thus giving the pixel, defined by each sphere, a white or black appearance.
In the 1990s another type of electronic paper was invented by Joseph Jacobson which used tiny microcapsules filled with electrically charged white particles suspended in a colored oil. In early versions, the underlying circuitry controlled whether the white particles were at the top of the capsule (so it looked white to the viewer) or at the bottom of the capsule (so the viewer saw the color of the oil). This was essentially a reintroduction of the well-known electrophoretic display technology, but the use of microcapsules allowed the display to be used on flexible plastic sheets instead of glass.
One early version of electronic paper consisted of a sheet of very small transparent capsules, each about 40 micrometers across. Each capsule contained an oily solution containing black dye (the electronic ink), with numerous white titanium dioxide particles suspended within the capsule. The particles are slightly negatively charged, and each one is naturally white. The microcapsules were held in a layer of liquid polymer, sandwiched between two arrays of electrodes, the electrode was made from indium tin oxide, a transparent conducting material. The two electrode arrays were aligned so that the sheet was divided into pixels, which each pixel corresponding to a pair of electrodes situated either side of the sheet. The sheet was laminated with transparent plastic for protection, resulting in an overall thickness of 80 micrometers, or twice that of ordinary paper.
On Oct. 18, 2005, E Ink Corporation announced an advanced electronic paper color prototype featuring 12-bit color in a 400×300 pixel format with a resolution of 83 pixels per inch. The display used a custom color filter from strategic partner Toppan Printing Co., LTD. and featured a high-brightness layout (RGBW) that preserves the paper-like whiteness of the background page while enabling deep blacks for text and a range of colors and tones for images.
Electronic paper has many applications and is particularly suitable for displays which are used in situations or applications in which a range of lighting and viewing angles are importance.
Electronic paper has been proposed for use in conjunction with banking cards, an example of which is U.S. Pat. No. 7,104,550 to Ramachandran that discloses a multifunction card that includes a programmable memory, a magnetic stripe, and an electronic ink display. The appearance of the electronic ink display can be changed in accordance with a selected account allowing a single multifunction card to substitute for many different cards.
U.S. Patent Application No. 20060065741 to Vayssiere discloses a smartcard that includes a dynamic display portion made of an electronic ink, in which the dynamic display portion changes from a first display to a second display in response to an application use of the smartcard.
Electronic paper typically requires a layer of microencapsulated electrophoric elements that are generally provided on a support sheet, a pair of electrodes situated on either side of the layer of microencapsulated electrophoric elements, a power supply, and an electronics package that includes a driver or power circuitry for operating the display. These components of electronic paper displays are exemplified by U.S. Pat. Nos. 6,639,578 to Comiskey, 5,930,026 to Jacobson et al. and International Publication Nos. WO 98/41899 to Jacobson et al. and WO 98/41898 to Turner et al, the entire disclosures of which are hereby expressly incorporated herein by reference.
The present invention provides a card that includes a changeable display that is based upon electronic paper technology. The card can be in the form of a credit card, smart card, bank card, debit card, ATM card, store card, gift card or any similar portable card.